According to new rankings from Cambridge, Mass.-based advisory and consulting firm Emerging Energy Research (EER), Spain-headquartered utility Iberdrola and Juno Beach, Fla.-based FPL Energy have emerged as leading generators of renewable energy.

Excluding large hydro, wind has grown to dominate the installed capacity of renewables over the last five years - representing 67%, or 21 GW, of the combined total capacity owned by the top 20 renewable producers, according to EER. Substantial wind power investments over the past five years contributed to Iberdrola's and FPL's rise to the top of the rankings.

In addition, the report found that renewables now drive significant merger and acquisition activity, such as Iberdrola's acquisition of ScottishPower. EER predicts that other European power companies such as Energias de Portugal, Enel SpA and Acciona Energia - which all recently acquired other firms - will move up the rankings at the end of 2007.